The spinal retractor of the invention is intended for surgical use for lumbar or dorsal laminectomies, or for spinal fusions, as mentioned above. Unlike most prior art lumbar spine retractors, the retractor of the invention is constructed so that its toothed blades do not have a tendency to slip out of the wound as the blades are spread apart. The blades are slidably received on the retractor arms, and they may be replaced by other different size blades, if so desired, for different size patients. As also mentioned, the configuration of the blades is such that the teeth serve to hold the lumbar muscles out of the way, to decrease the ischema and minimize necrosis of these muscles, and adequately to expose the facets.
In a first embodiment of the invention, a double rack is provided to allow for the creation of a significantly large blade spreading force as a pinion handle is turned. Moreover, the rack bars in that embodiment have no tendency to bow as the blades are spread apart.
In a second embodiment which is intended particularly for use in conjunction with microscopic lumbar laminectomy procedures, the blade configuration is similar to that of the first embodiment, but on a smaller scale. A single rack is used because the forces required are not as great as is the case in the intended field of use of the first embodiment.
In both embodiments the retractor arms are preferably hinged to allow for lordosis compensation. Also, the pinion handle is removable to provide a flat surface to assure that there are no impediments to the free movements of the surgeon's hands during the surgical procedure.
In the use of the retractor of both embodiments, the blades are first placed in the wound and set in the muscle above the facets. Once the blades are in the proper position, the retractor arms are inserted into the blades, and the retractor is operated so that the wound may be spread apart by the blades. This procedure allows for the precise placement of the retractor blades above the area of the facets, and it provides for better visualization of the spine.
As mentioned above, the lumbar retractor of the second embodiment is constructed particularly for microscopic procedures. When combined with a surgical microscope, the lumbar retractor of the second embodiment allows for superior visualization of the spinal structure through a small incision.
The retractors of both embodiments are usually provided with a set of variable depth blades for patients of different sizes. In both embodiments, the retractor blades have a sharp teeth design which hold the muscles and prevent the slipping upwardly of the blades to obviate any tendency for the blades to slip out of the wound. The blades are angled to fit the contour of the lumbar muscles and decrease the likelihood of blood circulation problems. Also, the construction is such that there is no tendency for the blades to rotate when the retractor is opened.